CO oxidation over the Cu2O/CuO hollow sphere heterojunction catalysts with enhanced low-temperature activities

In this work, a series of the Cu₂O/CuO hollow sphere heterojunction catalysts with various Cu⁺/Cu²⁺ ratios were designed and synthesized to improve the low-temperature catalytic activity of CO oxidation. The physicochemical properties of all the catalysts were characterized by the SEM, TGA, N₂-physisorption, XRD, FT-IR, XPS, and H₂-TPR. The results revealed that the Cu₂O hollow sphere catalyst had the large specific surface area due to the formation of the hollow structure, which could provid more accessible active sites for the gaseous reactants. Meanwhile, the Cu₂O/CuO hollow sphere heterojunction catalysts possessed high concentration of the surface oxygen vacancies and further promoted the adsorption and activation of O₂. As a result, the apparent activation energy of the CO oxidation was decreased and thus low-temperature activity of the CO oxidation was finally promoted. Therefore, the Cu₂O/CuO hollow sphere heterojunction catalysts were considered as a series of high-efficient catalyst candidates for CO oxidation with promising low-temperature performance.